Natural Gardening (free e-booklet)





Learn to grow healthy plants without hazardous chemicals and to recognize beneficial insects, common pests, weeds and plant diseases.


 <Download PDF - 954 KB>



Introduction ........................................................ iii   

Healthy yard and garden strategies ...................4

Least-harmful pest control strategies ................9

Water quality and household chemicals ..........10

Beneficial insects and others ............................11

  • Flower flies
  • Honeybees
  • Lacewings
  • Ladybird beetles
  • Mason bees
  • Parasitic wasps
  • Predaceous ground beetles
  • Spiders
  • Yellowjackets

Pests .....................................................................16

  • Ants
  • Aphids
  • Apple maggots Box elder bugs Carpenter ants
  • Carpet beetle Clothing moths Cockroaches
  • Codling moths
  • Crane fly larvae (European)
  • Cutworms
  • Earwigs
  • Elm leaf beetle
  • Fleas
  • Flies
  • Honeybee swarm
  • Imported cabbage worm
  • Indian meal moths
  • Leaf miners
  • Leaf rollers


  • Moles
  • Root weevils
  • Scale
  • Silverfish
  • Slugs
  • Sod webworms
  • Spider mites
  • Spiders
  • Symphylans
  • Tent caterpillars
  • Termites (damp wood)
  • Thrips
  • Wasps and yellow jackets

Weeds ...............................47

  • Blackberries
  • Bittercress
  • Clover
  • Dandelion
  • Horsetail rush
  • Morning glory
  • Moss
  • Poison oak
  • Quackgrass
  • Thistles

Diseases ...........................55

  • Black spot
  • Blight
  • Dogwood anthracnose
  • Powdery mildew
  • Rust
  • Scab

Glossary ...........................60

Resources .........................62

This book is a cooperative publication of Metro and the Oregon Department of Environmental Quality. It was originally produced for Metro’s natural gardening education program. The goal of the program is to educate home gardeners about less-toxic pest management practices in an effort to reduce the volume of pesticides entering the waste stream and regional waterways.  Metro is the agency responsible for solid waste disposal in the Portland metropolitan area and operates two household hazardous waste collection facilities. DEQ sponsors household hazardous waste collection across the state and promotes safe disposal of toxics.

  • Pesticides are the most expensive and among the most toxic materials to dispose of safely.
  • Pesticides disposed of improperly with garbage put waste handlers at risk of injury.
  • Pesticides should never go into the garbage, into the sewers or down storm drains.

Disclaimer. Neither Metro nor DEQ or any Metro or DEQ employees make any warranty, expressed or implied, or assume any legal liability or responsibility for the products or processes disclosed in this list. Reference herein to any specific product or process, service name or mark, trade name or trademark, or manufacturer or company does not constitute or imply an endorsement or recommendation by Metro or DEQ. The information herein is only intended to further the public interest by facilitating contact with entities engaged in supplying information or products related to integrated pest management.




While the environmental problems of the world may seem beyond your control, you can make a difference right in your own backyard.   Begin by learning good gardening strategies, many of which will result in fewer pest problems. Then learn how to use less harmful methods for managing insect pests, weeds and diseases in your yard before reaching for harmful chemical controls. 

This guide introduces some gardening tips that reduce pest occurrence and includes a hierarchy of steps to take before using harmful or polluting chemicals. Finally, it introduces some of the beneficial insects and pests common to the Pacific Northwest. Since it is not a comprehensive resource, refer to the Resources section for sources of additional information.

This document is reproduced in its full original text, with some notes added pertaining to field tested products shown to control a particular problem. Any Everwood Farm ® comments will be in this font and color and initialed


Natural gardening – it’ll grow on you!

Healthy Yard and Garden Strategies:

Had Benjamin Franklin considered the subject, he would have agreed that an ounce of prevention i s worth a pound of pesticides. There are many ways to prevent pest problems. Applying some or all of the following strategies will result in a healthier garden and help keep pest problems outside your garden gate.

Grow suitable plants

Native plants are often the best choice for trouble-free gardening. However, there are also many non-native plants like those from the Mediterranean that are adapted to a dry summer climate like we have in the Willamette Valley. Just be sure to avoid planting invasive non-native plants like English ivy, yellow flag iris, or vinca minor.

In addition to choosing plants that are adapted in general to our dry summer climate, it is very important to pick the right plants for each of your yard’s microclimates. Areas of shade, wet or dry soil, or varying wind and elevation levels each provide unique growing conditions. Picking plants that are well adapted to those conditions will reduce problems.

Many plants that are infamous for pest problems, such as roses, cherries and rhododendron, have cousins or look-a likes that are less prone to pests. Look for resistant varieties when choosing plants, and ask nursery personnel for advice. This is especially important for plants that are prone to diseases since there are few control alternatives to fungicides.

Garden in raised beds

Raised-bed vegetable and flower gardening is a great way to garden in Oregon. Raised beds allow for closer plantings, more root development, exceptional drainage (which is especially nice for those with heavy clay soil) and earlier springtime plantings. Raised beds require minimal paths, which means less space is needed to grow a fixed amount of food and flowers and less room for weeds to take hold. All told, raised beds can reduce your use of fertilizer, compost, water, and, if used, pesticides.

Studies show that chromium, copper and arsenic all leach from treated wood. If you decide to make raised beds, consider using untreated cedar, locust or cypress wood, which are naturally rot-resistant; or plastic lumber, which is made from recycled milk jugs and other plastic.

Practice garden diversity and crop rotation

One key to a healthy, stable garden ecosystem is a diversity of plants. A variety of flowers blooming throughout the growing season will provide nectar to beneficial insects who help you manage pests by eating or parasitizing them. Growing a diverse array of plant heights and shapes is also important. Trees, large and small shrubs, annuals, perennials and ground covers  combined provide important habitat for birds, bees, butterflies and other beneficial insects. If you grow vegetables, rotate planting locations for each type of vegetable from year to year. This will help prevent diseases and nematodes from building up in the soil and causing damage. To be most effective, planting areas should be large enough to allow plenty of distance and time between vegetables from the same family. Ideally, the rotation should extend for three or four years. 

Rotate vegetable plantings using the following listings as a guide. Do not plant two things from any of the following groups or families in the same place in consecutive seasons. If you will grow vegetables not included on these lists, rotate them each year as well.

• legumes and pod crops: okra, all beans, all peas

• alliums: all onions, leeks, garlic

• brassicas: kale, cauliflower, cabbage, brussels sprouts, broccoli, kohlrabi, rutabagas, turnips, radishes, bokchoi, oriental mustards, mizuna greens, others

• solanaceous, root and tuberous crops: any peppers, tomatoes, egg plant, potatoes, sweet potatoes, celery, beets, carrots, parsnips, others

Incorporating many types of plants into your landscape has numerous benefits. Diverse plantings provide food and cover for a variety of living things, including beneficial insects, that help your garden’s ecosystem. Diversity also minimizes the impact a specific pest will have on the overall visual effect of your garden, since many attack only one species of plant.

Foster fertile soil

Fertile soil is dark and crumbly and has a rich earthy smell. It absorbs and holds water like a sponge, breaths air like a lung and is teeming with life. Foster fertile soil, and your plants are less likely to have pest and disease problems.

Soil contains mineral particles (sand, silt and clay), pore space filled with air and water, and organic matter in various stages of decomposition. Organic matter is the stuff that at one time was part of a living animal or plant—manures, dead roots, leaves and insects and more. Organic matter is the key to soil fertility.

There are many ways to increase soil organic matter—compost, organic mulches, cover crops and more—and all will help support plant growth. Organic matter improves the structure of clay soils, allowing roots, water and air to penetrate, and it even helps sandy soil to hold water and nutrients. The addition of organic matter has these positive effects largely because it fosters organisms like bacteria, fungi and worms. These organisms not only enhance soil structure, but also continually (and amazingly) generate fertilizers from dead plant materials, tiny rocks and even from the air.

With soil rich in organic matter and soil organisms, you do not need to fertilize as much (or at all in some cases). If you do fertilize, remember that too much is as bad or worse than not enough—plants can grow too fast and become more susceptible to attack by diseases and pests. Excess nutrients can also run off the soil into storm drains and then pollute local rivers, lakes and streams. 

Organic fertilizers are more highly recommended than synthetic ones in part because they tend to last longer in the soil and hence are less likely to harm plants or local waterways. Many organic fertilizers also contain a broader array of essential plant nutrients, not just nitrogen, phosphorous and potassium (NPK). Finally, some organic fertilizers contain organic matter, which also benefits soil structure.  

To determine fertilizer needs, the first step is to pay attention to your plants. If they look healthy, chances are you need no fertilizer. If they are off color or attacked by disease or pests, you might have a nutrient deficiency or excess or a drainage problem. In this case, fix the drainage problem and get your soil tested (see Resources section).  A soil test will indicate if there are any deficiencies you can correct with fertilizers or soil amendments.

Use cover crops

Cover crops, also known as green manures, are an ideal way to protect and enrich your soil when it otherwise would be fallow for at least a month. 

If you don’t plant anything (cover crop or otherwise), nature will surely provide weeds. Cover cropping is an excellent way to naturally add organic matter and fertility to your garden soil, keep out weeds and protect the soil from erosion and compaction caused by winter rains.

Annual cool season cover crops are usually planted in the fall with the intention of mowing or tilling the plants into the soil in the spring. Some common cool season cover crops are fava beans, Austrian peas, crimson clover, hairy vetch and annual rye grass. During the warm season, quick growing buckwheat can be seeded anytime and then turned under as it flowers (about 30 days later).

Cover crop seeds are usually broadcast sown immediately after harvest or after the bed has been tilled or turned by hand. Simply sprinkle the seed evenly across the area to be planted, rake the bed lightly to settle the seed, then water.

Pay attention to your garden

One of the best things you can do for your garden is look at it. The English have a saying, “the best fertilizer is the owner’s footprints.” No matter How long you’ve been gardening, you are the expert in your own yard and will be the first to notice if something is amiss. If you inspect your plants regularly, perhaps ev ery other day, you will learn what plants tend to dry out more frequently than others, which ones are prone to aphids, when beneficial insects arrive to feed on pests, and many other interesting things. And most important, monitoring allows you to identify a pest occurrence before it becomes a problem. It’s much easier to deal with a small aphid colony than with 10 large aphid colonies. Monitoring is never having to say, “Where in the heck did that come from?”

Know a friend from a foe

To reduce pesticide use, learn what is and is not a pest. Many insects you’ll find in your yard neither help nor harm plants, and many others are helpful predators or parasites. When you see a “crawly thing,” figure out what it is before running for the bug spray. Even if you identify it as a plant eater, consider that the predators and parasites in your garden  would probably like to eat it much more than you would like to spray it. Also ask yourself if this one pest will cause damage that will adversely affect the whole plant. If not, let it go and spend your time on more fruitful endeavors, such as producing an environment that will result in healthy plants and lots of places for predators to thrive.

Least Harmful Pest Control Strategies

If you use all the tactics mentioned previously , you may never see a pest problem, and if pests do occur, their impact will probably be limited. However, despite your best efforts, unwanted pests sometimes take hold in the garden. In those cases, take the following steps to tackle the problem with pesticides as your last option.

Identify the problem

Before considering what control measure to use, correctly identify the pest, disease or weed you are facing. Nursery personnel are a good resource, as are many books in garden stores and the library. OSU Extension Master Gardeners or a county extension agent can be helpful. Keep in mind that most plant problems are not caused by insects or diseases at all, but are caused by inappropriate growing conditions. Furthermore, insects and diseases often attack plants that are already stressed from poor growing conditions.

Use appropriate controls

The choice of controls depends on the problem. Generally, options fall into the categories of hand removal, barriers, traps, biological control and least toxic chemical control. Once you understand how each tactic works, you can make informed decisions on their best use.

Hand removal

A sturdy blast of water can take out aphid populations, and pruning shears are all you need to control tent caterpillars. Removing diseased leaves, either by hand or rake, can help slow the spread of some plant diseases. These leaves should not go to the compost pile, however, since some
diseases may not be destroyed in the composting process. However, diseased leaves can go into curbside yard debris containers for recycling.


Barriers don’t kill pests. They simply keep pests away from the places you don’t want them. A good example is a screen door, which keeps flies out. Following are brief descriptions of common types of barriers:

Floating row covers: These thin, lightweight fabrics or plastics are placed over growing plants. They allow light, air and water to reach plants, but keep insects off. They are simply draped over the plants and secured on the sides with stones, wood or soil. As plants grow, they push the fabric up.

Netting: Netting is good for keeping birds off plants, especially as they come into fruit.

Copper slug barrier: Slugs cannot cross a 3-inch-wide sheet of copper. Sheet copper can be cut to size and attached to raised beds or planters, keeping slugs out. This method can also keep slugs in, so be sure to remove all slugs before banding. Also be sure to remove any plants that form a bridge between the outside and inside of the barrier. Apply banding vertically (like a fence) rather than horizontally (like a deck). It will continue to be effective after it has turned green. Despite the initial investment, this is an effective, inexpensive and long-lasting slug control tactic.

Sticky barrier: Marketed under the trade name Tanglefoot or Tangletrap, a sticky barrier will prevent insects and mites from walking up trunks of trees or shrubs. Note that root weevils walk, rather than fly, to the leaves of their hosts, so it can be used around the trunks of Rhododendrons (as long as there are no branches touching the ground) to stop their movement. Apply the sticky material to a wide piece of tape that is first wrapped around the trunk. Use this as a last resort as it can glue hummingbird beaks shut as they attempt to eat “tangled” insects.


All traps work by attracting and capturing a target pest. Traps work best when there isn’t much competition. For example, a slug might smell a slug trap in the middle of the garden, but it will also smell – and eat – many other tasty things along the way. Following are brief descriptions of common types of traps:

Sticky traps: These use a sticky barrier, such as Tanglefoot, with one or more attractants such as color, smell or shape, to bring the target pest in and keep it there. Yellow is a color commonly used since many insects associate yellow with flowers and, hence, plants.

Slug traps: Trapping slugs under small wooden boards, clay pots, overturned grapefruit rinds, or in shallow containers of beer at the soil surface can be a useful component to a larger plan to manage slugs. It is not, however, likely to be effective as a sole approach without a large investment of time (and beer, if that is what you use). 

Biological controls

Some of your garden’s best friends are natural enemies.

Biological controls, also called Beneficial’s, are “the good guys” that are hard at work eating insects, slugs, mites and other creatures in your landscape. Some have very specialized tastes; others will eat just about anything smaller and slower than they are. These heroes of the garden are described in the section titled “Beneficial Insects and Others.”

In all cases, Beneficial’s will come to your landscape and set up housekeeping if you provide them with the following basics. Put your energy into attracting them naturally rather than purchasing them at a nursery and releasing them. If conditions aren’t right to begin with, they’ll move on anyway.

Water:  This could be as small as a pebble-filled pie tin or bird bath, or as large as a pond, just as long as it is available and filled with fresh water all year.

A place to live: Every animal needs a home to protect it from enemies and raise its young. Although you can’t build little beneficial insect houses, you can grow them. Simply allow a variety of plants, including annual flowers, perennial flowers, bulbs, grasses, small shrubs, large shrubs, deciduous trees, and evergreen trees, to grow in your landscape. Organic mulches, rocks and snags (dead trees) also provide habitats. The Beneficial’s will find their niches.

An alternate food source: Pollen and nectar, mainly produced by flowers, sustain insect predators and parasites when insect food is not available. Vertebrates, such as birds and squirrels, will enjoy fruits, grain, seeds and other things, especially during the winter when other foods are scarce. Once the Beneficial’s get to know your landscape as a place to find food all year, they will keep coming back for the food you provide or the insects they pick off your plants.

Least-toxic chemical controls

Although using the practices mentioned previously will minimize, and possibly eliminate, the need for pesticides, there may be times when you choose to use them. In order to make informed decisions, it is important to understand them.

A few words about toxicity

All pesticides (synthetic and organic) are, by definition, toxic to some living thing – insecticides to insects, herbicides to weeds, fungicides to fungi, and so on. When a pesticide or any other material is described as “toxic,” it often makes people think of the effects the material has on human health. However, pesticides (and other chemicals) can also have toxic effects on the environment in which they are released.

There are many different ways to describe the toxicity of a material. For example, toxic effects on living organisms can be either acute (occurring immediately after the material is ingested or absorbed) or chronic (occurring after long-term exposure to the material). A substance may be short-lived (breaking down to harmless elements in a matter of hours or days) or persistent (remaining in their original state for months or years). Materials may bind readily to soil (making them more likely to remain in the site where they were applied) or may be very mobile (making them more likely to travel into surface or groundwater). Still others may be very soluble (dissolvable in water), volatile (likely to explode), or flammable (able to burn). In addition, some can cause secondary poisoning (direct or indirect effects on other living things that eat the original target). 

OMRI logoHere at Everwood Farm we are concerned about the safety of our clients and the environment. We have tried to choose wisely with regards to the pesticide products we carry. If you are an Organic Gardener, LOOK for the OMRI (Organic Materials Review Institute) logo on the products page. Click here for our product listing.

Is “organic pesticide” an oxymoron? How about “ synthetic organic?”

Ask a chemist what “organic” means, and he or she is likely to say, “contains carbon.” All living things contain carbon, so organic matter is simply the stuff that at one time was part of a living plant or animal. Some fertilizers and pesticides can be produced from animal and plant parts, thus they can be called organic as well. The word “synthetic,” when referring to garden products, means “created by humans: not occurring in nature.” Synthetic pesticides are chemical compounds invented in a laboratory. Ironically, those synthetic compounds that contain carbon can, technically, be called “synthetic organic.”

Note that although the word organic, when it is used to describe the way foods are grown, has come to imply “pesticide-free,” a more accurate definition of the term in this case might be “grown without synthetic pesticides.” Note also that some pesticides are not derived from plants or animals yet are still considered safe to use, and they are allowed in organic food production. Examples include insecticidal soap, horticultural oil, copper and sulfur. For more information about certified organic foods and food production, contact Oregon Tilth listed in the Resources section of this book.

The bottom line is this: no pesticide, synthetic or organic, is considered entirely “safe.” But, because of the effects on other living things, some are safer to use than others. Before selecting a pesticide, become informed about all the effects it may have. When you use any pesticide, follow all these points:

• Read and follow all label directions. Never use more than is recommended.

• Protect yourself. Wear a long-sleeved shirt, long pants, boots, rubber gloves, goggles, a hat and a respirator whenever mixing and applying pesticides of any kind.

• Never apply anything on a windy day.

• Only mix as much as you will use in one day.

• Dispose of empty containers properly. When a product label says “triple rinse the container,” rinse it three times, pour the rinsate into the sprayer and apply it to the target area according to label instructions. Wrap empty and/or rinsed containers in newspaper and dispose of them in your trash can. Home-use pesticide containers are not recyclable.

• Dispose of unwanted pesticides safely. Because pesticides are hazardous, they should never be disposed of in your garbage can or poured down the drain, into storm drains or onto the ground. Take them to a hazardous waste disposal facility or community collection event. In the Portland metropolitan area, call Metro

Recycling Information at (503) 234-3000 for details. Outside the Portland area, call your garbage hauler, local government s o l id waste department or the Oregon Department of Environmental Quality at (503) 229-5913 or toll free at 1-800-452-4011. For information about scheduled hazardous waste collection events across the state, call 1-800-732-925

Water Quality and Household Chemicals:

Many of the pesticides and fertilizers used at home can cause water quality problems miles away. Pesticides can pollute our region’s streams and rivers, harming fish, aquatic plants and animals, swimmers and those who eat the fish they catch.

Water from rain or irrigation carries pesticides and fertilizers from lawns and gardens into nearby street drains and into the groundwater. Many street drains feed directly to neighborhood waterways. Once in the water, pesticides dissolve, dilute or combine with other chemicals to create harmful combinations that can kill fish and aquatic life, limit beneficial plants and animals and increase growth of algae. Excess algal growth causes light deficiencies for plants and depletes oxygen levels that fish need to survive.

Clean water is an essential part of our quality of life. We can help protect our rivers, streams and lakes by rethinking and reducing our use of pesticides and other household chemicals.

Beneficial Insects and Others:

The following listings describe common beneficial insects that help control harmful insects. Other Beneficial’s include centipedes, dragonflies, damselflies, big-eyed bugs, predatory mites and many, many more. A very general rule of thumb for identifying a predator is this: if the jaws of the creature are pointing DOWN (that is, pointing at the surface they are walking on), they are plant-eaters. If the jaws are pointing OUT (that is, parallel to the surface they are walking on), they are predators.

In addition to these predators, there are many vertebrates such as birds, frogs, snakes, ducks, bats, mice, moles, squirrels and others snack on the eggs, larvae, pupae and adults of insects, mites and slugs.

Actual size: Adult 1/2” Larva 1/2”

Flower flies

Sometimes called hover or syrphid flies, these predators look somewhat like yellow jacket wasps but are much smaller and will not sting humans or other mammals. They are often found hovering near flowers, where they feed on pollen and nectar. Their larvae are legless and feed on aphids.


Actual size: adult 1/2” – 3/4”


Yellowjackets are picnic pests because they are attracted to the protein in chicken, hot dogs and other barbecue fare. When they aren’t at your barbecue, however, they are busy collecting insects to take back to the hive and feed the growing larvae. They are efficient predators, and do the gardener much more good than harm.

Actual size: 3/8” – 5/8”


Honeybees, although not predators, are very beneficial pollinators of many fruits and vegetables. Periodically a hive can become overcrowded and a large number of bees and a queen will leave to find a new home. These swarms, while spectacular to see, pose no real stinging threat since bees in a swarm are engorged with honey. The best way to deal with an unwanted swarm of bees is to call a reputable beekeeper who can, in 20 to 30 minutes, capture the queen bee. The rest of the swarm will follow. The swarm may leave on its own in as short a time as 30 minutes or remain clustered for as long as several days. (Calling the beekeeper, who wants the bees, as soon as possible will keep the bees from becoming pests in the neighborhood.) OSU Extension Master Gardeners keeps a listing of beekeepers. See the Resources section.

Actual size: Adult 3/4”


The most common lacewings are bright green insects with large gold eyes and delicate wings. They are about 3/4” long and eat pollen, honeydew and nectar. The larvae look something like tiny alligators, are tan, and eat aphids and other soft-bodied insects. A similar looking winged creature that is brown rather than green is the brown lacewing. It is also an effective aphid predator and is more tolerant of cool weather than the green lacewing.

Green Lacewing Product Link

Actual size: Adult 1/4” – 3/8” Larva 1/8” – 1/2”

Ladybird beetles

Better known as ladybugs, these black and red beetles are found throughout the world. There are thousands of species, many of which prefer only one or a few creatures for food. The most common species in Oregon eat aphids and other small, soft-bodied insects. The larvae of this beetle are usually black, 1/8” to 1/2” long, somewhat spiny, and look something like tiny alligators. They also eat many aphids.


Actual size: 3/8”

Mason bees

Orchard mason bees (Osmia lignaria) are small, shiny, blue-black native bees with gentle dispositions. They are not aggressive and one may observe them at very close range without fear of being stung, which makes them excellent for enhancing our yards and gardens. They add beauty, activity and pollination to our plantings.

Like many wild bees, they require a small cavity for their eggs, and are very particular about the size of the hole. It must be as close as possible to 5/16 of an inch, and optimally around 6 inches deep. There may be dense collections of individual nest holes, but these bees neither connect nor share nests; neither do they help provide for or protect each other’s young.

Orchard mason bees live for four to six weeks and appear in the spring when the temperature reaches 50 degrees Fahrenheit – about when fruit trees begin to bloom. The female mason bee visits flowers to collect pollen for her young. Her short foraging range is only about 100 yards from the nest that she builds with mud (hence the name “mason”).

Mason Bee tubes

Actual size: Adult 1/16” – 1/8”

Parasitic wasps

Most insects and many insect eggs are host to one or more species of parasitic wasps. Often tiny and delicate, parasitic wasps sting their host insects and lay eggs inside them. The eggs hatch inside the host and feed on it, eventually killing it. Aphids are commonly parasitized in this region, and some caterpillars are also attacked. Parasitic wasps are extremely effective at controlling insects, but are susceptible to most sprays. Parasitic wasps do not sting humans.

 View our "common pest" cross reference for parasitic wasp targets.

Actual size: 1/16” – 3/4”


Spiders are probably the best insect control in your yard. They eat a wide variety of insects and are very common.



Predaceous ground beetles

The large, glossy dark brown or black beetle with grooves down its back is a predator and will eat many insects





Actual size: 1/16” – 1”


There are many species of ants found in homes and gardens in the Northwest. Ants do not directly harm plants, but some actually “farm” aphids for their sugary excrement. If they are a nuisance, have your particular type identified by someone at a nursery or OSU Extension office. Also see the “Carpenter ants” listing.


Store food in tightly sealed containers. Keep all kitchen surfaces clean and free of food scraps and standing water.

Physical control

If a line of ants is marching across the kitchen, find the point of entry and seal it. Use a silicone seal. Use petroleum jelly for a short-term fix until you have time to do a better job. Remove what the ants are eating and mop them up with soapy water. Some have found that sprinkling red chili pepper at the entry point helps discourage ants. Wrap a band of tape, paper or cotton coated with a sticky substance such as Tanglefoot around the main stem of outdoor plants to trap ants.

Biological control

Birds, bee flies, humpback flies and thickheaded flies are natural predators outdoors.

Least-toxic chemical control

Diatomaceous earth, silica gel, boric acid and pyrethrum can be effective. Diatomaceous earth and silica gel are dusts that kill insects by drying them out. They are dangerous to breathe, so if they must be blown into wall spaces, a professional should do the job. Pyrethrum c an be combined with silica gel to give a faster effect; one form comes in a non-aerosol squeeze dispenser that allows application in cracks and crevices to minimize human and pet contact. Boric acid can be used in cracks, but only in areas not accessible to crawling children or pets. Prepare 1 percent boric acid solution by mixing 1 teaspoon boric acid, 6 tablespoons granulated sugar and 2 cups warm water. Store in a clear container. Use on cotton balls placed in the bottom of a plastic cup or tub with holes cut for ants to enter. Recharge each week. After three to four weeks, use 1/2 percent solution for continuous control. You can also use insecticidal soap to drench an ant colony outdoors or in a crawl space. More than one treatment may be necessary.

Actual size: 1/8”


More than 4,000 species of aphids have been identified. There are black, brown, red, purple, pink, green and yellow aphids. Some have wings and others do not. They all have a soft body about 1/8” long and a soda-straw mouth part adapted for extracting plant juices. Because aphids bear live young, their populations grow rapidly. Late in the fall, males are born to fertilize over-wintering eggs. These eggs, deposited in plant crevices and garden debris, withstand inclement weather to hatch in the spring. Most aphids excrete a sweet, sticky substance called honeydew as they feed. It serves as food for ants, bees and flies and as a growing medium for sooty mold. Aphids can transmit diseases between plants.

Prevention:  Avoid planting species that attract aphids. These include birch trees, roses and certain vegetable varieties such as Brussels sprouts. Consult your local county extension office or nursery for help choosing aphid-resistant plants. Also be sure that plants are healthy and have proper growing conditions. Weak or stressed plants are more susceptible to attack as are plants over fertilized with nitrogen.

Physical control:  For small infestations, hand pick or squish to destroy the aphids. On sturdy plants, use a strong spray of water to wash them off. If ants are also present, follow the steps outlined in the “Ants” section.

Biological control:  Aphid predators include syrphid flies, green lacewing larvae and ladybugs (also called ladybird beetles). Chalcid and braconid wasps are aphid parasites. Parasite and predator populations often lag behind aphid populations, so there may be periods in the year, particularly in the spring, when the aphids appear to be out of control. Often the predators can catch up and restore control, but be patient. Remember to provide the basics: water, shelter and food. Plants may develop some damage but should outgrow it. If pesticides are applied when predator populations are present, they may be harmed and prevented from keeping aphids in check.

Ladybugs and lacewings can be effective in controlling aphids. They are available from many nurseries. Before introducing any predators, reduce aphid numbers by pinching off severely affected plant parts or hosing off most of the aphids. For best results with ladybugs, choose the right time of year and time of day to release them. Ladybugs are most active when the
weather is warm, from April through September. Dusk is the best time of day to release them. Water the foliage where the aphids are feeding. The hungry and thirsty ladybugs will be attracted to the water-drenched foliage and find the aphids for food. They do have a tendency to disperse when released.

Both the ladybug adult and larvae are predators. Green lacewing larvae are also effective predators of aphids and can be purchased and released.

Least-toxic chemical control

Insecticidal soap sprays are often very effective in controlling aphids, although you may need repeat applications. To make your own, mix 1- tablespoon Castile or ivory soap in one gallon of water. Spray on infested plant parts. (This also works for mites.) It is important to use pure soap only. Detergent can burn plants. Insecticidal soap are also widely available in nurseries. Use rotenone, sabadilla or pyrethrum only as a last resort for severe infestations. A dormant oil spray applied in the winter may smother over-wintering aphid eggs, but you may want to wait to take action until the problem reappears.

Actual size: Adult 1/4” Maggot 1/4”

Apple maggots

This pest makes brown tunnels inside apples with external symptoms so slight they may go unnoticed. The adult apple maggot is a fly, similar to the common housefly. Flies lay their eggs in the apples and the legless white maggots develop in the flesh of the fruit. The insect spends the winter in the soil in its pupal stage.

Physical control;  Collect dropped apples to reduce the apple maggot population. If not too badly damaged, these apples can be made into cider or you can compost them.  Trap adult flies with a solution of one part blackstrap molasses or malt extract, nine parts water and enough yeast to create fermentation. Once the fermentation subsides, pour the liquid into wide-mouthed jars, coffee cans or milk cartons. Hang the containers in the trees as traps

Another effective trap is a red plastic sphere, made sticky by applying a commercially available sticky compound such as Tanglefoot, hung in trees to trap the insects when they land. These traps are available at garden centers or can be made at home. Avoid sticky traps if hummingbirds are likely to be present as their beaks can be glued shut by them.

If apple maggots are a consistent problem, consider planting thicker skinned later varieties such as Winesap and Jonathan.

Biological control

Yellow and red sticky boards, available at garden centers, attract apple maggot flies. The flies are drawn to the color and are caught on the trap’s sticky surface.

Actual size: 1/2”

Boxelder bugs

These bugs feed on the ash trees. Full-grown boxelder bugs are about 1/2” long with reddish brown or black bodies and red lines. The young are bright red. After feeding on plants in your yard during the summer, boxelder bugs may enter your house for a warm place to winter. However, they will not feed on anything and will not cause damage.

Physical control:  For smaller infestations, try hand picking the bugs. Reduce their numbers by removing nearby unwanted female box elder trees (they produce the seeds). Inside, sweep them up and dispose of them. If you use a vacuum, dispose of the bag so bugs can’t crawl back out once the vacuum is stored away or place the bag in the freezer for a few days to kill the bugs. Also, seal cracks in exterior walls and around windows. Look for boxelder bugs in warm, sunny places in spring, such as on the south side of a house. They tend to congregate under such conditions and can be vacuumed up with little effort.

Least-toxic chemical control

Spraying box elder bugs with insecticidal soap may help with their control. However, soap may stain some painted surfaces if it is not washed off immediately.

Carpenter ants

Unlike termites, carpenter ants don’t actually eat wood. They nest in it. If you find them in your house, look for a good professional who understands your concerns about toxic chemicals and will work with you to select a least- toxic control program. While they can cause serious damage to houses, these ants are actually beneficial insects in the forest, where their excavations help speed the decomposition of dead trees. In fact, they prefer to build their nests in decayed or rotted wood, but will eventually extend their tunneling into sound wood if they can’t find decayed wood.

Positive identification requires collecting a few of the largest ants and inspecting them under a magnifying glass. Carpenter ants have a smooth upper back, while most other ants have a dip in this area. Suspicious signs include sawdust and debris, rustling sounds in the walls and trails of ants between the foundation and wood outside the home.

Carpenter ants eat dead insects, honeydew exuded from aphids, plant juices and sweet or fatty foods in the home. To assess the extent of the problem, locate the main colony. Seventy-five percent of all main nests are located outside the house where there is abundant moisture, such as in an old tree or tree stump above or below the soil surface. Satellite nests may be found inside your house, in walls and ceilings, under outdoor siding, near downspouts or roof gutters, in floors – particularly bathrooms – or in insulation. Begin with the basement and work up to the attic, looking for the ants and sawdust-like wood shavings.


Remedy whatever attracts them to your house in the first place. Repair any rotten or weather-damaged wood and make sure that attic and crawl space ventilation i s adequate. Inspect gutters and downspouts to be sure they do not leak and that water is being diverted away from the house. Clean out the gutters. Remove any wood in contact with soil at any part of the house, porch, deck, etc. Firewood should not be piled against the side of the house. It should be elevated off the ground and kept away from the house. Trees and shrubs should be pruned back so that they do not touch the house or garage, including roofs. Stumps should be completely removed. Even decorative bark may harbor carpenter ants and provide nesting sites.

Physical control

Locate and remove all nests, capture stray ants, caulk access points and replace all damaged wood. This sounds like a tall order, but if the infestation is accessible and has not spread too far, you can be successful.

Least-toxic chemical control

Use desiccating dusts, such as diatomaceous earth or silica aerogel. Boric acid is a powder that can be blown into wall voids. Pyrethrum i s also effective. This small beetle eats articles made of natural fibers, like wool sweaters and cotton or linen apparel. They leave an unmistakable calling card: their shed skins in the bottom of drawers and holes in articles stored there.

Biological Controls:

Carpet beetles


The most effective control measure is to prevent infestations of carpet beetles. The best way to do this is to store items in a clean condition; beetle larvae are attracted to soiled areas, especially food stains. Store infrequently used items (that are clean) in well-sealed plastic bags or containers. Sachets made from rosemary, mint, thyme and cloves help repel these pests. Check cut flowers for adult carpet beetles before you bring them into the house.

Least-toxic chemical control

If you discover beetles inside the house, apply boric acid to the areas in which you find them.

Actual size: Wingspan 3/8” – 1 3/8”

Clothing moths

These moths are very small, no longer than 1/2”. They like to settle in dark places such as stored clothing or under furniture slipcovers, where they leave their eggs. The eggs hatch into larvae, which feed on anything containing wool, fur or feathers. They will also eat other fabrics if dirty and blended with wool. They are primarily attracted to dirt, lint, salt, stains, moisture and dead insects.


Clean any used clothing or furniture you purchase before bringing them inside. Keep stored clothes and furniture clean and dry. Minimize humidity with good ventilation and control moisture sources.

Physical controls

Vacuum rugs, furniture and closets frequently. Clean out drawers used to store clothing. Store clothes in airtight containers or bags sealed with tape. While cedar and natural sachets smell wonderful, they are not effective at repelling moths. Shake out or brush clothing you wear infrequently t o destroy any larvae present. Expose to air and sunlight. Placing clothing items in the freezer for several days will kill clothing moth adults and larvae.

Actual size: 1/2” – 5/8”


These six-legged, hard-bodied insects can carry disease, contaminate food and induce allergies. They hide in cracks and crevices during the day and feed at night on water and food crumbs, even wallpaper paste or envelope glue. They prefer warm, moist areas such as kitchens, bathrooms and around washing machines and hot water heaters.


Cleanliness is crucial. Properly store and dispose of all kitchen wastes. Keep the kitchen clean and free of food scraps. Wash dishes immediately after eating. Keep areas where grease accumulates clean . Wash pastry cloths. Do not leave pet food or water bowls out at night. Enclose food in sealed containers. Fix dripping faucets and other leaks and make sure your dish rack drains properly. Damp, dirty mops can also attract roaches. Sweep frequently.

Physical control

If you find a cockroach nest, wash and vacuum the area if it is accessible. Plug cracks around baseboards, cupboards, pipes, sinks and water heaters with latex or silicone caulk. Move debris, firewood and garbage away from the house.

Least-toxic chemical control

Use boric acid, but keep it away from areas children or pets may explore. It is particularly useful under the stove and refrigerator or in cracks that cannot easily be plugged. Use roach traps that contain boric acid to monitor the effectiveness of your prevention and control measures.

Actual size: Moth wingspan 3/4”  Larva 1”


Codling moth

Codling moths emerge in the spring and lay eggs that hatch into larvae that pupate during late summer and fall. Codling moth larvae are a unique white color tinged pink with a brown head. They tunnel directly to the core of fruit, usually apples or pears.

Physical control

Wrap bands of burlap or corrugated cardboard around tree trunks just after bloom, before caterpillars begin to move down the tree (late spring) and maintain them through fall. This draws larvae looking for a place to pupate. Use several thicknesses and wire or tie them on. The corrugated cardboard ridges should be 3/16” wide and face toward the tree with the ridges running vertically. Remove the bands once a week in warm weather (every two weeks in cooler weather) and kill the larvae. Continue until you have harvested all the fruit. Even in the best situations, banding will control only a small percentage of codling moths because many pupate elsewhere in the tree or drop to the ground, bypassing the trunk.

Scrape away loose bark and destroy over-wintering cocoons before warm spring weather.

Biological control

Garden centers carry pheromone traps that attract the male moths and kill them. Trichogramma wasps and braconid wasp larvae are natural parasites of moths. These wasps are available through various mail-order companies. You can attract parasitic insects by growing a wide variety of flowering plants like sweet alyssum or daisies nearby to provide a good nectar source.

Bt (Bacillus thuringiensis) has been used with some success to help control codling moths. However, to be effective, applications must be frequent and carefully timed to reach the larvae just as they hatch. Be aware that Bt will kill moth and butterfly larvae indiscriminately.

Least-toxic chemical control

Horticultural oil spray or ryania, a botanical insecticide, may be applied as eggs are laid and before they hatch. Time these sprays to coincide with moth catches in pheromone traps.

Actual size:  Larvae 1” – 1 1/2”

Crane fly larvae (European)

European crane fly is a recent arrival in Oregon and looks much like the variety commonly found here. Adult crane flies look like giant mosquitoes, and are sometimes called mosquito hawks or mosquito eaters. The common variety is harmless and usually found around marsh areas. Crane fly larvae or grubs are worm-like insects up to 1 1/2” long that live in the soil and destroy grass roots, crowns and shoots, leaving brown patches in the lawn.


Crane flies are attracted to soggy areas of your lawn, so minimize watering and/or improve drainage.

Physical control

Begin monitoring for larvae in early spring. Shorten the grass in one square-foot patches in several places around your yard. Pour warm water mixed with a little soap (not detergent) on the patch and count the grubs that emerge. If levels are above 25 grubs per square foot, treatment may be appropriate. Consult with the OSU Extension service for treatment options. A warm, dry fall may reduce the number of larvae because of their sensitivity to dryness.

Research in Colorado has shown that aerator shoes that strap onto your feet can be used to control grubs. The long spikes on the bottom of the aerator shoes pierce the grubs as you walk over the infected sod. Also, thatching or aerating the lawn can reduce populations. Do these treatments on a cool, moist day when grubs are at the surface.

More than 100 species of birds are known to feed on crane fly larvae. Crane fly larvae are among starlings’ favorite foods.

Biological control

Beneficial nematodes are effective when applied to the sod according to package directions. Use it once soil temperature rises above 55 degrees, usually in late spring, when the crane fly is in its larval stage.

Actual size: Adult 1 1/2” wingspan  Caterpillar 1” – 2”


Cutworms are gray or brownish caterpillars that curl up when disturbed. They feed at night and hide in the soil during the day. Eggs are laid in the soil, and the larvae or pupae overwinter in the soil. A sure sign of cutworms is sliced-off stems of seedlings at soil level.

Physical control

Protect individual seedlings with a 3” tube made from stiff paper or plastic pressed 1” into the ground. Toilet paper tubes work well as do film canisters with the lid removed and bottom cut off. Spread cornmeal or molasses near the base of each plant. Cornmeal wells up inside worms when they
eat it, killing them. Molasses immobilizes them, but is effective only during dry weather.

Biological control

Beneficial nematodes or Bt (Bacillus thuringiensis) can be used. Follow package directions and apply under recommended conditions. Bt is most effective with younger, smaller cutworms.

Actual size:  3/8” – 5/8”


Earwigs are brown, beetle-like insects distinguished by a pair of long pincers at the tail end. Earwigs are scavengers of decaying matter and predators of insect eggs and larvae, slug eggs, snails and other slow-moving bugs. They are nocturnal feeders, spending the day under bark, stones and garden trash. They occasionally feed on foliage, flowers and other parts of many plants, including dahlias, zinnias, corn, hollyhock, lettuce, strawberries, celery, potatoes, seedling beans and beets. They usually come into the house only as transients and won’t stay unless there is plant material for them to eat.

Physical control

Set sections of bamboo or damp rolled up newspapers horizontally through the garden or flower beds. Check the traps early each morning and dump the insects into a bucket of soapy water. Empty tuna cans containing 1/2” of vegetable oil also attract and drown earwigs.

Actual size: 1/4”

Elm leaf beetles

Elm leaf beetles are generally found on the big American, Siberian and Chinese elm trees and on zelkova, occasionally planted in place of elm. In spring, the adults lay eggs on the leaves. When the eggs hatch, the immature beetles eat all the fleshy parts of the leaf, leaving only the skeleton or veins. After a month or so, they are ready to pupate into the cocoon stage and descend to the base of the elm. They are about 1/4” long, and usually yellowish or golden in color with black markings.

Physical control

Because the pupae are visible on the ground around the tree, you can destroy them by simply smashing them. The elm leaf beetle can produce as many as three generations in the summer, which can seriously weaken the tree.

After feeding on plants in your yard during the summer, beetles try to enter your house during the fall for a warm place to winter. However, they do not feed on anything inside and will not damage your home. Sweep them up and dispose of them. If you use a vacuum, dispose of the bag so they cannot escape after the vacuum is stored away, or place the bag in the freezer for several days to kill the beetles.

Biological control

Check with your nursery for a specific variety of Bt (Bacillus thuringiensis var. san diego) that attacks beetle larvae. Tachinid flies and chalcid wasps are effective enemies of elm leaf beetles.

Least-toxic chemical control

Summer oil can control elm leaf beetle eggs and can be applied in the spring.


Actual size: Adult fleas – 1/16”


Fleas are a common pest west of the Cascades where winters are mild and homes are relatively damp. They inflict annoying bites, transmit tapeworms and can cause allergies in both animals and humans. Fleas are almost impossible to eradicate. You may kill most of the adults, but new eggs or larvae are waiting to carry on, and your pet will bring in more fleas from outside. Don’t dismay. You can keep the flea population low enough that it won’t be bothersome, and you can do it without using highly toxic products.

Decide at what level a flea problem becomes unacceptable to you. This may be one flea bite per week or finding two fleas each time you comb your pet. When fleas reach an unacceptable level, apply control measures starting with the physical ones. At any time, fleas may exist in all four life cycle stages (egg, larva, pupa and adult) in your home. Follow these recommendations closely and use chemical controls only if necessary.

Physical control

Establish one regular sleeping area for your pet in a place you can clean easily and regularly. This is easier for dogs than for cats. With cats, you may have to place removable cloths in several places where they like to sleep. Any bedding materials and nearby rugs should be removed frequently and washed. Vacuum all areas to which your pets have access every week with a strong canister-type machine. Use a crevice tool and don’t forget the upholstered furniture. During the “flea season” in the late summer and fall, you may need to vacuum more often – every third day or so. Dispose of the vacuum bag immediately so that the fleas cannot escape after the vacuum is stored away.

Severe flea outbreaks may require shampooing or steam cleaning rugs and upholstered furniture. Restrict your pets to certain rooms in the house. Do not allow them in bedrooms, hard-to-clean rooms such as basements and attics, or rooms belonging to family members particularly susceptible to flea bites. In severe cases, keep animals either outside or inside, but don’t let them go back and forth. Small areas outside where your pet spends a lot of time (concrete areas, dog houses, garages or decks) can be kept relatively free of fleas by vacuuming. However, it is better to focus your efforts indoors, where you have more control.

To remove adult fleas from pets, comb them with a flea comb and bathe them. A flea comb has specially designed tines spaced to allow hair, but not fleas, to pass through. Several tine spacings are available. As you run the comb through your pet’s fur, some fleas will jump away, but others will stay on the comb. Remove the fleas from the comb and drop them into a container of soapy water. When finished, flush them down the toilet. Count the fleas removed to estimate the flea population and monitor the need for other controls. Shampooing an animal knocks some fleas off and drowns others. Ordinary soap or shampoo work to a degree, but an insecticidal shampoo is more effective (see below). Keep the soap away from the pet’s eyes and stop using any product that produces skin irritation or allergies.

Least-toxic chemical control

Flea collars are not recommended because they contain very potent chemicals that may harm your pet. The safest chemical for killing fleas is an insecticidal soap. Separate soaps can be purchased for treating the pet and its surroundings. There are also insecticidal soap sprays available for inside/outside use to which a small amount of pyrethrum is added. Many other pyrethrum-based products are available. Cats are especially sensitive to pyrethrum, so if your cat does not tolerate it, try something else.

After soaps, the safest chemicals to kill adult fleas are the natural constituents of lemon peel oil, which are quite toxic to adult fleas and relatively safe to vertebrates. Use shampoos or area sprays that contain linalool. Do not substitute these products for a year-round program of non-chemical control.

Lufenuron (Program), also known as “flea birth control,” is a once-a month oral medication veterinarians can prescribe for pets. Fleas that feed on a dog or cat treated with the drug produce eggs that are unable to develop. When administered to all pets in a household, the treatment can be effective in reducing indoor flea populations. Because it does not kill adult fleas or prevent new fleas from being introduced from outside, it should be used in combination with other controls. Tests performed on dogs and cats taking lufenuron for two consecutive summers revealed no obvious side effects. However, because long-term toxicity studies have not yet been published, possible cumulative effects on pets are unknown.

Imidaclopril (Advantage) and fipronil (Frontline) are liquid formulations that are applied externally in one spot on the animal’s back and kill adult fleas. They are effective for one month. They work by spreading over the body through skin oils, and kill fleas within 24 hours.

Methoprene, an insect growth regulator, mimics natural insect hormones and prevents immature fleas from becoming adults. It is quite specific to the target insect and is fairly safe to mammals. However, it does not kill adult fleas or eggs, so it must be used in combination with other controls. It is more effective when flea populations are just beginning to build, but you may not know that the problem is going to be serious enough to need chemical treatment. Methoprene is available in aerosol foggers and a concentrate. Foggers are not recommended because they do not concentrate the application in the areas where adults and larvae hide (carpets, bedding, etc.) and often contain other toxic ingredients. Spray the concentrate as directed.

Boric acid can be applied on inside carpets and diatomaceous earth can be spread over lawns. These materials kill fleas by drying them out instead of poisoning them, but are dangerous to humans, especially young children, if inhaled or absorbed through a cut in the skin. Wear rubber gloves and breathing protection when applying these yourself or have them applied by professionals. Avoid these methods if you have young children.

Actual size: 1/8” – 1/4”


There are many different types of flies, but only four kinds are found indoors and are considered house pests. The common house f ly is gray and about 1/4” long. It breeds in garbage cans, dumpsters, compost piles or other sources of food waste. It can pose a health hazard because it carries disease organisms. The drain fly is somewhat smaller and breeds in sewage and kitchen drains. The tiny yellow-brown fruit fly hovers over fruits and vegetables in the kitchen. The fourth type, the cluster fly, is not associated with garbage or manure. It is larger and darker than the housefly, is a sluggish flier and is often found in clusters on windowsills in winter.


The key is to prevent odors. Properly store and dispose of all kitchen wastes. Keep the kitchen clean and free of food scraps and overripe fruit. Wash dishes immediately after eating and keep drains fresh with baking soda and vinegar, followed with hot water. Rinse recyclable cans and bottles before storing. Bury or dispose of pet feces. Install properly fitting screens on windows and doors and keep them in good repair.

Physical control

The best way to dispense with a fly is the old-fashioned way, with a fly swatter. You can also try rolls of sticky flypaper, particularly in garages, near garbage cans and other areas where appearance is not important. These methods should control cluster flies, but will be inadequate for controlling the other types of flies unless proper sanitation practices are followed. Try a saucer of red wine to attract and drown fruit flies.

Ultraviolet light and electrocution traps are not recommended for outside use because they kill as many beneficial insects as they do flies. Chemical insecticides, including impregnated hanging strips, are not recommended as they pose risks to human health and should not be needed if the source of the problem is addressed.

Actual size: 3/8” – 5/8”

Honeybee swarm

The best way to remove a swarm of bees is to call a reputable bee keeper who can, in 20 to 30 minutes, capture the queen bee. The rest of the swarm will follow. Bees in a swarm are engorged with honey and pose very little stinging threat. OSU Master Gardeners keep a list of beekeepers willing to come get the swarm.


Actual Size: Butterfly 1” – 2” Larva 1 1/4”

Imported cabbageworm

Adult imported cabbageworms are the white butterflies (with black tips and 2-3 spots on each wing) that flit about in the garden for almost the entire growing season. The larvae, which are medium green, eat large, ragged holes in leaves of cabbage-family plants and cabbage heads and soil the leaves with dark green excrement.


Cover plants with a floating row cover all season or until fully mature.

Physical control

Hand-picking imported cabbageworm larvae in light infestations can be very effective. Eggs are conical and light in color and are laid on the undersides of leaves of cabbage family plants such as broccoli and cauliflower. They can be scraped away easily with your fingernail. Use yellow sticky traps to catch female butterflies.

Biological control

The relatively docile paper wasps, which pose no threat to humans, are known to eat imported cabbageworm larvae (caterpillars) and other softbodied insects such as aphids. Larvae may be controlled with Bt (Bacillus thuringiensis). Be aware that Bt will kill moth and butterfly larvae indiscriminately.

Actual size: Wingspan 5/8”

Indian meal moths

Indian meal moth larvae are generally brought home in purchased food such as cereal, flour, oatmeal, trail mix, etc. The larvae may stay in the food, feeding on it all year. When it emerges, it seeks out the warmest place, which, in your house, is the ceiling. If you miss seeing them in their pupae stage, you probably won’t miss the adult moth fluttering around in your house.


Never leave opened packages of food in your pantry. Always store food in sealed containers. If you have a problem with a particular dry good, store it in the freezer. This also kills the eggs in food that is already infested.  Freezing newly purchased packages for 24-48 hours will usually destroy all eggs.

Physical control

The best solution is to check your dry goods and find the container where the moth has laid her eggs and larvae have hatched. As the larvae feed, they make webs that look like spider web strands tangled up in the infested food. Put the infested food in a sealed paper bag and dispose of it. Pheromone traps for catching Indian meal moth adults are available commercially.

Leaf miner damage Size: Adult 1/10” Larva 1/4”

Leaf miners

Leaf miners are insects that tunnel between the upper and lower surfaces of leaves. Hatching larvae tunnel through the mid-leaf tissue, feeding as they go, and leave characteristic wavy lines that are visible on the top of the leaf. When ready to pupate, the larvae leave the leaf and drop to the soil, emerging in 10 to 15 days as adult flies. A certain amount of tunneling can usually be tolerated, but the damage is especially troublesome on spinach, chard and sometimes beets since these plants are grown in order to harvest the leaves.

Covering the vegetable crop with a floating row cover for the entire life of the plants can be extremely effective. Fall-sown crops are less susceptible. Move plantings at least several feet away from where you planted last year.

Physical control

For small infestations, pick off and destroy the affected leaves. Scratch the small white egg clusters from the backs of the leaves with your fingernail. In enclosed areas such as greenhouses, use yellow sticky traps to catch adults. Plastic mulches prevent leaf miner larvae from reaching the soil to pupate.

Biological control

Encourage beneficial predators such as lacewings and spiders for egg and adult control. Other natural enemies include ants, true bugs, flies and birds. Parasitic wasps are able to attack the larvae through the leaf.

Controlling Leaf miners in the garden

Least-toxic chemical control

Neem oil operates as a repellent to adult leaf miners and as a systemic insect growth regulator on larvae. Recent studies also indicate that horticultural oils (not dormant oils) may work against leaf miner eggs, but timing the spray is crucial.

Actual size: Moth 3/4” Larva up to 1”

Leaf rollers

There are many types of leaf rollers that infest many different plants, including apple, willow and plum trees, blueberries, photinia and laurel. The larval stage is a caterpillar that folds the leaf and webs it, then feeds inside it.

Physical control

Remove them or the leaves they are in from the plant. Do not put them in your compost bin unless you bury the leaves in the deepest, hottest part. It is better to put them in a sealed paper bag and place it in the garbage.

Biological control

Encourage native parasitic wasps such as Trichogramma. Bt (Bacillus thuringiensis) , the bacterium that paralyzes the digestive system of the pest, may be used according to label directions. However it is difficult to deliver to the areas where the larvae are feeding. The rolled leaves provide good protection.

Least-toxic chemical control

Dust or spray with pyrethrum or rotenone for severe infestations only. Apply in two applications, 30 minutes apart. The first drives the caterpillars from hiding, the second kills them.

Actual size: 7”


Some moles are beneficial – they eat pest insects and improve the soil through aeration. Some, such as the Townsend’s mole, which is found here in the Northwest, eat more vegetation than do other species. All moles eat earthworms, and all species, regardless of their feeding habits, can disfigure lawns, heave up seedlings and sever tender roots as a result of tunneling. Sometimes, though, moles get blamed for damage done by field mice or gophers.


Since mole damage is most noticeable and problematic in lawns, one solution is to replace some or all of your lawn with garden beds. If this is not practical, you may want to first try castor oil repellants. This approach is not always effective and may require repeated applications every 30-60 days. Presence of a dog and excessively dry soil has been reported by some to discourage moles. In extreme situations, ¼-inch wire mesh can be buried 18-24 inches deep around the perimeter of a garden or lawn.

Physical control

Lethal trapping is the most effective and reliable method for controlling moles, but it is pretty tricky. You need to have good hand strength and to carefully follow manufacturer’s instructions for setting traps. Scissors and harpoon style traps are reportedly some of the more effective. Use of lethal traps for moles requires a permit from the Department of Fish and Wildlife in the state of Washington.

Actual size: Adults 1/4”

Root weevils

Root weevils commonly infest the root systems of ornamental shrubs such as azalea, primrose, rhododendron and small fruits such as blueberry and strawberry.

Larvae live in the ground around the base of a plant and chew on the bark and the surrounding surface roots primarily during the fall and winter months. Adult root weevils are nocturnal feeders, notching the edges of the leaves, and are most active from late spring through summer.

Physical control

Prune any branches that are touching the ground to prevent adults from crawling up them to feed. Rake any mulch away from the stem to reduce their hiding places. You can apply a collar with a band of a sticky substance such as Tanglefoot around the base of the trunk to trap them and prevent them from reaching their food source. Handpicking the
adults at night is an effective control method.

Biological control

Use beneficial nematodes available at a nursery or garden center. When the nematodes are rehydrated, they attack and kill the root weevil larvae. This treatment is effective in early fall. Follow label instructions.

Least-toxic chemical control

Use Neem to control adults in early summer. Applying diatomaceous earth around plants may help in dry weather. Wear nose and mouth protection when applying, and keep pets away from the area.

Actual size:  Adult female 1/100” – 1/10”


There are many varieties of scale, which suck plant sap, weakening plants and causing leaves to yellow and drop. Some excrete large quantities of honeydew. There are two to four larval stages. The first looks like a mite and subsequent stages look like smaller versions of the adult females. Adult females look like hard or soft bumps on stems, leaves and fruit. Males, minute flying insects with yellow wings, do not feed.

Physical control

For small infestations, hand picking or dabbing scale with rubbing alcohol is effective. Prune and dispose of infested branches and twigs.

Biological control

Encourage predators such as aphid lions (green lacewing larvae), syrphid fly larvae, ladybugs (adults and larvae) and parasitic wasps.

Least-toxic chemical control

Use insecticidal soap or horticultural oil spray in early summer on the crawler stage. Repeat applications every 3-4 days are recommended. Do not use oil sprays when the plant is flowering. Apply dormant oil spray only in the winter, or it may defoliate your plant.

Actual size: 3/8” – 1/2”


Silverfish are attracted to carbohydrate substances such as the glue on the back of wallpaper or in the spine of books. They can be a problem in boxes where books are stored. They are attracted to dark, damp areas.

Least-toxic chemical control

Boric acid can be applied on inside carpets and applied in hard-to-reach cracks using spray or powder in a duster bottle with a needle-nose applicator. Never use in areas where crawling children or pets may have contact

Actual size: 1/8” – 5”


Slugs feed at night and prefer moist plant material. They eat many types of vegetables, fruits and flowers. Some of their favorites are strawberries, lettuce, spinach, carrot tops, dahlias and marigolds.


Remove garden debris, boards, bricks and tall grass where slugs may hide during the day. Select plants that are not favored by slugs in your area by paying attention to those with minimal damage in your own or neighbor’s yards. Consider planting seedlings or plants large enough to withstand some damage instead of sowing seed. A 3-inch wide band of copper foil or sheeting attached to the vertical sides of a raised bed around the entire perimeter forms an effective barrier. Be sure clear out all slugs inside the barrier or they will not be able to get out, and remove any plants that form a bridge into the bed from the outside.

Physical control

Do a “search and destroy” mission at night by patrolling your yard with a flashlight and killing the slugs you find. You can cut them in two with scissors or drop them into a bucket of soapy water. Trapping slugs under small wooden boards, clay pots, overturned grapefruit rinds, or in shallow containers of beer at the soil surface can be a useful component to a larger plan to manage slugs. It is not, however, likely to be effective as a sole approach without a large investment of time (and beer, if that is what you use).

Least-toxic chemical control

A new type of “natural” slug bait is now available for use in the United States. Brand names include Sluggo, Escar-go! and Worry free. The active ingredient in these products is iron phosphate. It is apparently much safer around pets and wildlife than more commonly used metaldehyde-based slug baits. The EPA has not identified any sub-chronic, chronic, immune, endocrine or other problems with iron phosphate. According to the manufacturer of Sluggo, the inert ingredients are food additives and are biodegradable.

Iron phosphate may not be fatal to all species of slugs found in the region, but it does give 85 to 100 percent control of two common garden slugs. Baits remain active for about a week or longer, depending on the environment. After eating the bait, the slugs almost immediately stop feeding and start drying out. They die after three to six days.


Actual size:

Moth wingspan 1/2 “ – 1 1/2” Larva 1/2”

Sod webworms

The larvae of this lawn moth feeds on the shoot and crown of the grass, but not the roots. Irregular brown patches appear on the turf and the grass dies back, leaving irregularly sized dead areas. The 1/2” larvae are slender and gray with brown heads. They can be seen when the damaged sod is lifted.

Physical control

Dethatch lawn and reduce clover and dichondra numbers to help minimize damage.

Biological control

Beneficial nematodes and Bacillius thurengensis sub sp. Kurstaki (Bt) are also treatment options. Be sure follow label instructions

.Actual size:  1/64”

Spider mites

Spider mites are found on a wide variety of plants. If the leaves start to look pale or mottled, it may be from mites sucking the juices. They are almost too small to see, but can be identified by tapping a suspect leaf over a sheet of white paper. If the little spots move, it’s likely they are mites. You may also be able to see webbing on the back of the leaf or between leaves. Spider mites especially like dry conditions. If spider mites have been a problem on your house plants, try raising the humidity around the plants by misting them regularly or setting bowls of water among them.

Physical control

Wash spider mites off with a strong stream of water. You will need to repeat this every several days. Be sure to spray all sides of the leaves thoroughly. Daily misting with water can also reduce mites by making conditions less hospitable for them.

Biological control

Predatory mites, available from nurseries, prey on all types of harmful mites but are most effective in greenhouses. Ladybugs, praying mantis and lacewing larvae also eat mites.

Least-toxic chemical control

Try insecticidal soap, which is effective when sprayed directly on the mites. Repeated applications may be necessary. Light horticultural or summer oil can also be effective. Avoid spraying when the plant is flowering. Pyrethrin and sabadilla are less-toxic treatments, but do pose risks to aquatic organisms and bees.

Actual size:  1/16 “ – 3/4”


Spiders are beneficial predators that consume many destructive insects. There are many types, but only black widow spiders and hobo spiders pose any threat to humans in our area. Hobo spiders build funnel-shaped webs in crawl spaces, wood piles, or around the perimeters of homes. They rarely climb vertical surfaces and are uncommon above basements or ground level. They wait inside the tube and dash out to bite any prey that becomes entangled in the web. They can grow to 3/4” long and may bite intruders with little provocation. Bites are touch sensitive and cause a severe headache in the first several hours following the bite. Bites can be serious and should be treated.


Keep tall weeds and grasses away from the house. Shut basement and first floor windows tight or use screens. Make sure the bottoms of doors have insulation stripping that can keep spiders from entering. Avoid areas where spiders congregate.

Physical control

The best way to get rid of a spider in your home is to place a glass jar over it, slip a card underneath and carry it outside. They are fragile and will usually be killed by sweeping with a broom. Spraying with a pesticide is usually pointless because woodpiles and similar areas are so attractive to spiders that they usually return.

Actual size: 1/20” – 1/4”


Symphylans, sometimes called garden centipedes, are found in rich, moist soils.  Symphylans are about 1/4” long at their largest, white, have 12 pairs of legs, and feed on plant roots. Note that true centipedes have 15 pairs of legs and eat other insects, so correct identification is very important.

Symphylans are usually brought into a landscape in manure or compost and thrive in very moist soils high in organic matter. They feed on the roots of many different plants and, in high numbers, can kill young starts. Older plants often can outgrow the damage as long as they have adequate water. Susceptible plants include tomatoes, lettuce, sugar beets, chrysanthemum, asparagus, beans, brassicas, celery, cucumber, parsley, peas, peppers, potatoes and strawberries.

Symphylans are especially difficult to get rid of once they have become established in a garden. None of the following suggestions are foolproof, but, when used together, can probably reduce their numbers.


The best bet for symphylan control is to not get them in the first place. If you are bringing in manure to add to the garden, look it over with a magnifying glass for symphylans before applying it. If your soil tends to be wet, be careful not to over apply organic matter, don’t use organic matter as your only source of fertilizer or consider moving the garden to a drier location. If they inhabit your compost pile, eliminate that pile and resume composting on a plastic sheet or concrete slab. Symphylans tend to occur in spots in the garden, so crop rotation into non-susceptible plants may help.

Biological control

Beneficial nematodes may help to control symphylans. Be sure to follow label directions.

Physical control

If the site is level and on the wet side, you can try flooding the area for several days in winter to drown symphylans. Or, cover the site with plastic on a sunny, warm day to heat the site and kill the pests. Symphylans are fairly delicate creatures, and cultivation will also help reduce their numbers.

Rototill in the spring and fall and hand cultivate around plants during the season to stir up the soil and destroy symphylans.

Least-toxic chemical control

Neem has been shown in laboratory studies to reduce symphylan numbers.

Actual size: Up to 3”

Tent caterpillars

These caterpillars spin the silky white tents that cover the tips of branches. They damage plants by eating foliage as it emerges. They eat leaves off many deciduous trees and shrubs, especially walnut, alder, willow, fruit trees and roses. If a tent has been on a branch for awhile, chances are some caterpillars are fully grown (up to 3”) and have left the tent to select a site to spin cocoons. After about two weeks, adult moths emerge, mate, lay eggs and die. The eggs are laid in a foam-like band around small twigs or branches of the host tree where they hibernate over the winter. When new leaves begin to appear in the spring, the eggs hatch.

Physical control

Consider tolerating a few tents. These caterpillars are native insects and are controlled in the long term by natural factors. Prune out branches containing tents in particularly valued trees or those with heavy infestations. Prune early in the morning or in the evening when caterpillars are in their tents. Put tents in a sealed paper bag in the garbage. During the winter, examine branches and rub off egg masses that appear as hardened gray or brown frothy material, somewhat similar to Styrofoam®. Egg masses are usually 1/2” long bands surrounding twigs. Deposit in a bag, seal it and place it in the trash.

Biological control

Tachinid flies deposit white eggs, natural parasites, in visible rows on the caterpillars’ backs. If you look closely at the caterpillars and see these eggs, natural controls are working. You can introduce the bacterium Bt (Bacillus thuringiensis ), but to be effective, it must be sprayed to thoroughly coat the leaves since Bt is a stomach poison effective only when ingested. Bt will kill all caterpillars, including those that mature into desirable butterflies. If you use Bt, use it only on the affected plant and follow label directions.

Actual size: 3/4” – 1”

Termites (damp wood)

These termites land on your house, shed their wings and try to find a home. They will die if they cannot find damp wood.


Do not leave soil piled up next to your house or in contact with any wood structures. Also, repair any leaky pipes that keep surrounding wood moist. Firewood should be stored in a dry place; wet wood attracts termites.


Actual size: Up to 1/5”


Thrips are tiny, elongated, fast-moving insects 1/5” long or less. Adults and nymphs suck sap from plant tissue, leaving silvery spots or streaks on leaves. In the Pacific Northwest, thrips are a particular problem on gladiolus, but in general do not cause much more than cosmetic damage. Thrips can apparently produce young without mating. The process, which is also common in aphids, permits a very rapid population buildup.

Physical control

In greenhouses, hanging blue sticky traps helps catch adults before they move onto plants.

Biological control

Encourage native predators such as lacewings and lady beetles. Because most thrips pupate in the soil, they are potentially susceptible to insect eating nematodes. Two predatory mites also appear to have substantial potential for thrips control.

Least-toxic chemical control

Insecticidal soap or horticultural oils can be used to provide temporary relief from thrips while you are waiting for predators to arrive. As a last resort, spray with neem, pyrethrin or sabadilla. You can also apply diatomaceous earth just on the undersides of leaves and on soil around affected plants.

Actual size: 1/2” – 3/4”

Wasps and yellow jackets

Wasps and yellow jackets are beneficial. They eat other insects. If they become a nuisance, use traps specifically designed to capture the type of pest you have. Consult a knowledgeable nursery person  for advice on which one to use. Place traps away from high-use areas. Traps only work early in the season (before August).


Cover garbage cans and outdoor foods, especially fruit and other sweets.



Although there are blackberries native to this region, the species of blackberry that is most invasive is the Himalayan blackberry, an imported species that has naturalized here. It is, however, a source of food and cover for many species of wildlife, not to mention the source of countless jars of blackberry jam. It arrives in your landscape via seed in bird droppings or by the invasive roots that creep under fences and out of naturalized areas.

Nothing other than hard labor and natural decomposition will make the canes go away. Furthermore, no herbicide will completely control the roots, so if you use physical methods or chemical methods to control blackberries, continual, persistent removal of the new growth will be necessary for at least a year following your initial efforts.


Encourage the growth of desirable plants, especially vigorous shrubs that will cover the ground, and use mulches wherever possible.

Physical control

Remove canes by hand and pull as many roots as possible. Wear leather gloves, a long-sleeved shirt and long pants to protect yourself from the thorns. Winter is an especially good time since the heavy clothing will be more comfortable and the leaves will be off the plants, making them a little easier to work through. During the growing season, continue to remove the new canes as they appear. Also, remember that if a site has been neglected for a very long time, this will be heavy, uncomfortable work. Do yourself a favor and be realistic about how much area you can clear in a day.

Least-toxic chemical control

If chemical control is necessary, it is preferable not to spray, but rather to paint a systemic herbicide on the leaves while the plant is actively growing. The herbicide will move through the plant to kill the roots.



This member of the mustard family has a circle of leaves at its base and produces 6” to 8” stems with white flowers. The flowers mature into inch long seeds that pop off when disturbed. This plant is prolific only in the spring; by summer, it should be no problem.


In flower or ornamental plant beds, use a deep organic mulch to reduce their numbers.

Physical control

In late February, before the flowers go to seed, manually pull them or hoe them. If you manually remove them early in the season as soon as they start to grow, the seeds won’t spread and increase the problem.


Clover comes in many varieties, all three-leafed and low lying. Clover spreads mostly by creeping stems or seeds. Clover can be a useful addition to eco- lawn—it has nice flowers and symbiotic bacterial in its roots that fix nitrogen from the air, making it available to the lawn over time. It does however attract honey bees, and one variety (burr clover) has seeds that attach to clothing and pet fur.


Clover in lawn is often associated with an excess of phosphorous and low nitrogen. Maintaining balanced nutrient levels in the soil for lawns can help to prevent infestations, but not control them. If your soil does need fertilizer, it is best to apply in fall and in general, the recommended Nitrogen to Phosphorous to Potassium (N-P-K) ratio should be around 5-2-3. Do not over fertilize—nutrients can run off and contaminate local waterways. A thick, healthy lawn mowed relatively high and watered for a maximum of one inch per week will also help prevent the spread of clover. Clover in garden beds can be prevented with a thick mulch or dense plantings.

Physical control

In lawns, hand pulling and immediately re-seeding with turfgrass seed is recommended for effective clover control. In garden beds hand pulling and mulching or dense plantings are recommended. In pathways and paving cracks, a weed flamer can provide effective management.

Least toxic chemical control

Potassium salts of fatty acids, and new clove and acetic acid combinations are effective for a broad spectrum of annual and young perennial weeds including clover. These products are most useful for pathways and paving cracks as they are non-selective.


Dandelions have a long thick tap root that stores food reserves. Dandelion seeds are dispersed by wind.


Minimize them by not allowing the flower to go to seed. Mow lawns often to keep the flowers from maturing. In flower or ornamental plant beds, use a deep organic mulch to reduce their numbers.

Physical control

Hand dig them out, removing as much of the root as possible. In lawns, removing dandelions leaves small bare areas where new weed seed can germinate. Spread a little grass seed in those spots to prevent weeds from establishing.

Horsetail rush

Horsetail rush is an ancient plant that can be attractive in natural settings, but easily becomes a pest in the garden. It spreads by spores or by its root system, which can be as deep as 12’. Its presence indicates that the soil is wet clay, tending to be acidic. Try drying out the area if possible. Or consider planting other water-loving plants, such as rushes and sedges, to add a more natural element to your landscape.

Physical control

Hand pull or hoe out the above ground growth as it appears. Persistence is necessary, but over time, this will deplete its energy reserves and achieve control. When the weed dies down in winter, cover the area with weed barrier cloth and leave in place for two years to prevent weeds from photosynthesizing. Even then, roots may still be able to push up new growth.

Morning glory

Morning glory is a weedy vine that will twine all over the garden, covering plants to the point of smothering them. It is usually spread by seed or invasive roots. Its thick fleshy roots can travel long distances just under the soil surface.

Physical control

Hand weeding can remove large quantities of roots, but any broken pieces are capable of sprouting new growth. Never dispose of morning glory in your compost pile. Repeated, persistent digging or rototilling as the new growth sprouts can deplete the food reserves and allow other plants to compete successfully. Keeping all green parts removed from mid-summer to late fall will starve the roots and help control morning glory and other perennial weeds. Be persistent; it can take a long time to eliminate morning glory from your yard.

Least-toxic chemical control

If chemical control is required, do not spray. Paint the leaves with the least-toxic systemic herbicide available when the plant is actively feeding its roots. A systemic will move from the leaves through the plant’s vascular system to kill the roots. Do not put plant parts that have been treated with herbicides into your compost pile.


Moss is a natural part of the Pacific Northwest’s native ground cover. If your lawn has moss, consider leaving it there or allowing it to spread in planting beds to form an attractive ground cover. It prefers shade, moisture and poor acid soils.


Correct the conditions that encourage moss to grow. Water infrequently but deeply, making sure that the water is penetrating and not running off.

Proper aeration and thatching of lawns will help air flow. Do not apply water faster than the soil can absorb it. Soil should be limed as necessary to correct pH and fertilized or amended to encourage the growth of desired plants or turf. If trees shade an area, consider pruning them to introduce more sunlight.

Physical control

Rake moss out of lawns with a thatch rake.

Least-toxic chemical control

For temporary relief, apply an herbicidal soap or an iron-based product that turns the moss black as it dies. Keep these products off concrete, as they will stain, and keep them from running off into local waterways

Poison oak

In the open or in filtered sun, poison oak grows as a dense leafy shrub. Where shaded, it becomes a climbing vine. Its leaves are divided into three leaflets. Poison ivy, which grows in eastern Oregon, is very similar, but it is more sprawling in growth habit and rarely climbs. The foliage of both turns bright orange or scarlet in the fall.


Poison oak will eventually die out if you keep it clipped to within an inch or two of the ground with a power mower or hand clippers. Grasses tend to crowd it out so it can’t get enough height to put out leaves.

Physical control

Woody perennials, such as poison oak and wild blackberries, have high reproductive capacities, and established plants are difficult to eradicate by digging. But it is not impossible. Mulching is the easiest way to rid yourself of stubborn perennial weeds, but it may take a year or two. Grub out rootstocks and mulch heavily. Mulch options include corrugated cardboard, 10 to 20 sheets of weighted newspapers and landscape fabric.

To eradicate young plants, put on a long-sleeved jacket and leather gloves and pull them out by hand as soon as they appear.

Biological control

If the plant is young and not woody, goats, if managed properly, can be helpful in eliminating woodier weeds such as poison oak and ivy, wild blackberry, bamboo and scotch broom.

Least-toxic chemical control

If plants persist, paint the leaves with the least-toxic systemic herbicide available rather than spraying.


Quackgrass forms dense spreading mats with white, fleshy roots.

Physical control

Keep pulling it out. Pieces of root left in the soil can sprout new growth. Sift the soil carefully to make sure you remove all root pieces. Try covering it with weed barrier cloth. If mowed regularly, quackgrass does
not seriously detract from the appearance of a lawn. Mowing will gradually cause quackgrass to decline.

Least-toxic chemical control

Hand-pull from lawn and be sure to re-seed bare spots with an appropriate grass seed. If quackgrass persists and you need it to be gone, do not spray. Paint the leaves when they are about 8” high with the least- toxic systemic herbicide available when the plant is actively feeding its roots. A systemic will move from the leaves through the plant’s vascular system and kill the roots. Do not put plant parts that have been treated with herbicides into your compost pile.


Thistles have leaves with sharp prickles and spread by seed or
underground shoots.


In flower or ornamental plant beds, use a deep organic mulch to reduce their numbers.

Physical and least-toxic chemical control

Pull them out and cover troublesome areas with weed barrier cloth. Spot treat with potassium salts of fatty acids or acetic acid-clove combinations.


Black spot

Black spot is a fungus common to rose bushes. Symptoms appear as coal- black lesions on upper and lower surfaces of leaves. Heavily diseased leaves tend to turn yellow and drop prematurely. When excessive premature defoliation occurs, the plant forms a new set of leaves, which causes a considerable drain on food reserves in the roots. This results in a weakened plant with poorly matured wood. A few days after the spots first appear, little black pimples show up in the spots; this signals that the spores are about to be discharged and you should act fast to remove and discard those leaves. Spores are carried by air currents, insects, tools, hands and clothing.


When selecting a rose bush to buy, consult a knowledgeable nursery person or the OSU Extension agent or Master Gardeners for varieties that are less prone to black spot. Some varieties are more susceptible than others.

Physical control

Remove infected leaves from the bush and those already fallen on the ground so they can’t re-infect the plant. Prune away excess foliage and sickly canes to improve air circulation. In the spring, remove the mulch around the base of the plant and rake the ground thoroughly to expose it to the sun. When new shoots appear, apply generous amounts of new mulch. Never water roses from overhead in the evening. Keep the foliage as dry as possible because dry leaves are less likely to support the fungus.

Least-toxic chemical control

Dust with a finely ground sulfur when temperatures are under 85 degrees. It tends to burn leaves if applied in very hot weather.


The term “blight” is used to refer to a great number of plant diseases that affect a number of plants in one area, rather than isolated cases. Most blights are caused by pathogenic organisms, generally fungi, but sometimes bacteria, and are manifested by browning foliage, reduced vigor and death of the plant. Early and late blight, which strikes potatoes and tomatoes, and brown rot blossom blight, which affects cherries, peaches and plums, are common in the region. Blights spread readily when plants are wet. A warm, humid spring increases the chance of blight problems. Warmer, drier weather may check the spread of blight.


Most diseases including blights are almost impossible to eliminate once they have taken hold of a plant. The best we can hope for is to try to prevent them from starting and, if that fails, to prevent them from spreading. Blight-resistant varieties of plants are available. Don’t water tomatoes overhead at night. The foliage can’t dry off and this increases the potential for blight problems.

Physical control

As mentioned above, once the plant is infected with blight, it is virtually impossible to control. Pick off and destroy infected parts when you spot the first sign to prevent the disease from spreading.

Least-toxic chemical control

A fungicide spray of copper may be effective in preventing late blight on tomatoes and brown rot blossom blight on fruit trees.

Dogwood anthracnose

Not to be confused with the disease of oaks, maples, sycamores and other plants, anthracnose is a common name used for many unrelated plant diseases that cause leaf spots and dieback. Because of its lethal effects on many species of dogwood, this particular fungus has earned the scientific name Discula destructiva. It attacks most species of dogwood, including flowering dogwood and our native dogwood, but does not occur on Korean (also known as kousa) dogwood.

Diseased plants typically have spots on the leaves and flowers that are light to dark brown with purplish margins. These spots produce spores, which spread via wind and rain to other leaves and create more spots. Severely infected trees will have poor growth, produce few leaves, small leaves and many sprouts at or near the base of the tree, and will eventually decline and die.


Whenever possible, plant kousa dogwoods. They are lovely trees, with dark, glossy green leaves and creamy white flowers. There is at least one pink-flowering variety available as well. They bloom after other dogwoods, usually in June.

Physical control

Rake up diseased leaves and remove them. Prune the tree to increase air circulation, which may lessen the occurrence of leaf spots. Also, infected trees often produce many sprouts at or near the base of the tree, which are especially susceptible to infection. These should be removed. Finally, be sure the tree receives adequate water, preferably from an irrigation source that does not wet the leaves.

Least-toxic chemical control

The only effective control is a chemical leaf spray available only through tree care companies. It must be applied several times a year, beginning in early spring.

Powdery mildew

Powdery mildew is a white or grayish powdery coating on the surfaces of leaves, stems and buds. It germinates on dry leaves in high humidity and is commonly found on fruit trees, roses and big shade trees. Rain inhibits it and warm, damp nights encourage it. It can cause stunting and distortion of leaves, buds and growing tips, a general decline in plant growth, yellowing of leaves and premature leaf fall.

Physical control

Prune and thin out excess branches to increase air circulation. Plant resistant varieties, and put them in sunny locations.

Least-toxic chemical control

Sulfur sprayed or dusted on the plant can prevent spread of mildew to new growth. Alternatively, spray with a mixture of 1 gallon water, 3 teaspoons baking soda, 2 1/2 tablespoons horticultural oil and 1/2 teaspoon insecticidal soap. Spray this on an unobtrusive area of your plant first, and watch for signs of adverse effects before spraying your entire plant.


Rust is a fungus with orange to brownish pustules on the underside and pale yellow spots on the tops of grass blades, snapdragon or hollyhock leaves, raspberries and rose bushes. It is common on Kentucky bluegrass and on the weed annual bluegrass.


Pick off and destroy affected leaves as soon as they are noticed. Leaves must be wet for four hours to become infected, so careful watering can help prevent it.

Mow the lawn shorter to improve air circulation and apply a nitrogen predominant fertilizer that contains sulfur. Choose a grass seed mixture containing fine fescues and perennial rye grass, two species that are less susceptible to rust.

Least-toxic chemical control

Periodic dustings of sulfur have been found to be somewhat effective, but you should not need this unless preventive measures have failed. Sulfur can be highly irritating to the respiratory system. Wear nose and mouth protection when applying.


Scab is a name given to several fungus diseases. One infects apple and other fruit trees, another infects cucumbers and yet another can infect potatoes. On fruit trees, scab generally appears first on the undersides of the leaves as pale yellow spots that gradually darken until they are nearly black. Leaves may have numerous scab spots and become distorted. The scab fungus over winters on the fallen infected leaves, producing spores in spring. The spores are wind borne and infect the young leaves and fruit during periods of rain. Warm rainy weather is ideal for scab.


For potatoes, scab is particularly severe in alkaline soils and usually worse in dry soil. Avoid using lime, fresh manure or wood ashes on your potato beds, as these will increase the alkalinity. If potato scab has been a problem, you should practice a three to five-year crop rotation schedule. Always plant resistant varieties of potatoes and apples.

Physical control

Because the fruit tree fungus spends the winter on fallen infected leaves, rake them up carefully and dispose of them. Careful pruning for good air circulation creates a less favorable environment for the spread of scab.

Least-toxic chemical control

Dormant lime sulfur sprayed on the fruit trees during the winter will help control it. In the spring, if your plants are in serious trouble, continue using lime-sulfur spray or wettable sulfur.


Bacillus thuringiensis (Bt)

a bacteria used to control certain pest larvae, primarily caterpillars. Bt is not toxic to humans or other mammals but will kill butterfly (“friendly”) caterpillars as well as the problem ones. The bacteria kills larvae by interfering with digestion. Bt lasts on leaf surfaces five to seven days and must be ingested to be effective. There are many strains of Bt commercially available now, including strains for controlling mosquito and beetle larvae.

Boric acid

slow acting, low-toxicity, long-lasting (if kept dry) powder that is effective against ants, cockroaches and other structural pests. It is a digestive and contact poison and is usually applied as a dust. Products often come with a duster-type applicator. It is toxic if ingested, inhaled or comes into contact with abraded or broken skin. It poses a risk to children and pets if they come into contact with it. It is safe to place it in wall voids because it does not evaporate and cannot enter living spaces.

Diatomaceous earth

Made from ground up fossils, it comes in a powder form and is very abrasive. It is a dust that abrades the skin and body joints of insects. Dry diatomaceous earth makes a marginally effective slug barrier. Do not inhale the dust.

Dormant oils

Act by coating the plant surface and suffocating any insects that are present. Target pests are aphids, mites, scale insects, whiteflies and eggs of many pests, including some caterpillars.

Dormant oils are meant for use on leafless, deciduous plants (especially fruit trees) in the winter to reduce pest populations before they hatch. If used in summer, these oils might defoliate the tree.

Horticultural oils

Also called summer oils, these are more highly refined than dormant oils, making them appropriate for use on leaves during the growing season. Consult a nursery to locate a suitable product and follow all precautions. Don’t use horticultural oils when plants are flowering.

Insecticidal soaps

Highly refined liquid soaps (technically the potassium salt of fatty acids), sometimes combined with citrus oil. Soaps are normally mixed with water and sprayed onto leaves to control spider mites, aphids, scale insects, Whiteflies and other soft- bodied insects. They are contact insecticides, meaning you must wet the pest for them to be effective. As always, follow package directions and cautions when using these products.


A relatively new botanical insecticide derived from a tree. This product is reported to be very effective, with slightly more staying power than some other botanical insecticides. It does, however, break down completely and is less toxic to humans than some botanicals.


A chemical substance produced by insects and animals that stimulates certain behavior of other members of the same species. Traps use female pheromones to attract males and prevent reproduction.


An effective, short-lived, naturally derived insecticide made from chrysanthemum flowers. It is toxic to all insects, including beneficial ones, and moderately toxic to birds and mammals. It should be the last resort for ornamentals and is not recommended on food crops. Avoid using formulations that contain piperonyl butoxide, which is currently being evaluated for its carcinogenicity. Pyrethrins are the individual chemicals found in pyrethrum. Pyrethroids are a new array of synthetic chemicals, such as cyfluthrin and cypermethrin. They resist breaking down, thus negating their major environmental advantage. With the three names being so similar, they can easily be confused. Pyrethrum is the least hazardous.


A tropical plant-derived insecticide that is harmful to insects, fish, birds and mammals. Read labels to see if the product is mixed with other pesticides. Check the label to see if the pest problem and the plant you want to protect are listed. It is toxic and should be handled with care. Follow label instructions exactly.


A shrub native to South America is the source of this insecticide. It incapacitates fruit moths, corn borers, codling moths and imported cabbage worms. As always, read the label before you buy to see what other ingredients may be mixed with it and if it is safe to use on your particular plants.


The seeds of this South and Central American plant are ground into a powerful insecticidal dust. It is effective against grasshoppers, codling moth larva, webworm, aphid, cabbage looper, chinch bug and many household pests. It can irritate mucous membranes and cause sneezing. Honeybees are vulnerable to it. Handle it carefully.


OSU gardening publications are available through OSU Extension and Experiment Station Communications at:
Search for "Gardening Information"

Oregon Tilth
470 Lancaster Drive, NE Salem, OR 97303

Metro Recycling Information
600 NE Grand Ave. Portland, OR 97232

> Call for information inside the Portland metropolitan area:

  • detailed “alternatives” fact sheets on controlling specific pests and weeds
  • a free booklet about hazardous household products and less-toxic alternatives
  • information about free natural gardening workshops
  • disposal of unwanted yard and home chemicals through Metro's household hazardous waste program
  • home composting, general recycling and waste disposal information.

Oregon Department of Environmental Quality
811 SW Sixth Ave. Portland, OR 97204

Northwest Coalition for Alternatives to Pesticides
PO Box 1393, Eugene, OR 97440

Washington Toxics Coalition
4649 Sunnyside Ave. N
Suite 540 East, Seattle, WA 98103

Bio-Integral Resource Center
PO Box 7414, Berkeley, CA 94707

Soil and Water Conservation Society
in cooperation with USDA Natural Resources Conservation Service, 2000


Natural Gardening <Download PDF - 954 KB>
A cooperative publication of Metro and the Oregon Department of Environmental Quality.

Ellis, Barbara W. and Bradley, Fern Marshall
The Organic Gardener's Handbook of Natural Insect and Disease Control
Rodale Press, 1996

Jeavons, John
How to Grow More Vegetables: Fruits, Nuts, Berries, Grains and Other Crops
Ten Speed Press, 1995

Kourik, Robert
Designing and Maintaining Your Edible Landscape Naturally
Metamorphic Press, 1986

Lovejoy, Ann
Ann Lovejoy's Organic Design School: A Guide to Creating Your Own Beautiful, Easy-Care Garden
Rodale Press, 2001

Mac's Field Guide
Good Garden Bugs/Bag Garden Bugs of the Pacific Northwest

The Mountaineers, 1997

Olkowski, William
The Gardener's Guide to Common-Sense Pest Control
Taunton Press, 1995

Rodale, Maria
Maria Rodale's Organic Gardening:
Your Seasonal Companion to Creating a Beautiful and Delicious Garden

Rodale Press, 1998

Schultz, Warren
The Chemical-Free Lawn
Rodale Press, 1989

Smittle, Delilah
Rodale's Complete Garden Problem Solver
Rodale Press, 1996

Solomon, Steve
Growing Vegetables West of the Cascades (5th Edition)
Sasquatch Books, 2000

Wasowski, Andy and Wasowski, Sally
The Landscaping Revolution
Contemporary Books, 2000

Organic Gardening Magazine
Rodale Press, Emmaus, PABio-Integral Resource Center

Soil and Water Conservation Society
in cooperation with USDA Natural Resources Conservation Service, 2000
Soil Biology Primer

Least Toxic Lawn Management
PO Box 7414
Berkeley, CA 94707



Custom Left Slide Out

You can add any content here, text, images, etc.

your alt text here